DESCRIPTION: This is a resubmission of a previous grant. The investigators propose to assess the outcomes of a "natural experiment" to determine whether aggressive early detection and treatment efforts are effective at reducing prostate cancer mortality for Medicare beneficiaries. In the United States, clinicians in the Seattle SEER area were much more aggressive in trying to detect prostate cancer early (particularly with the prostate-specific antigen or PSA test) and treat it aggressively (particularly "PSA era" (1987-1990). During the pre-PSA era, population-based prostate cancer mortality in these two are and was essentially identical. Their natural experiment focuses primarily on cohorts of about 75,000 men in Seattle and 95,000 men Connecticut who were age 65-74 (with at least a 10-year life expectancy) and who were residents of their respective regions through at least through 1990. During the period 1987-1990, they have already determined that the men in the Seattle cohort were about twice as likely to undergo prostate biopsy, twice as likely to be diagnosed with prostate cancer, and six times as likely to undergo a radical prostatectomy than men in the Connecticut cohort. In fact, the cumulative incidence of radical prostatectomy in the Seattle cohort from 1987- 1997 was over 3% (about the proportion of men in this cohort who would ultimately be expected to die of prostate cancer) compared to less than 1% in the Connecticut cohort. They propose to continue follow-up of these two cohorts through calendar year 2001, or 15 years from inceptions of the cohorts. Over this interval, they would expect to see a reduction in population-based prostate cancer mortality Seattle as compared to Connecticut if early detection and aggressive treatment as actually practiced in the community are indeed an effective strategy.